Ultrastructural study of spermatogenesis in<Emphasis Type="Italic"> Phoronopsis harmeri</Emphasis> (Lophophorata,Phoronida) |
| |
Authors: | Email author" target="_blank">Arkadiy?ReunovEmail author Waltraud?Klepal |
| |
Institution: | (1) Institute of Marine Biology, Far East Branch of the Russian Academy of Sciences, 690041 Vladivostok, Russia;(2) Institute for Zoology, University of Vienna, Biozentrum, 14 Althanstrasse, 1090 Vienna, Austria |
| |
Abstract: | The process of sperm development in Phoronopsis harmeri was studied by electron microscopy. Developing spermatogenical cells are aggregated around the capillaries of the haemal plexus. The spermatogonia, which are situated around the capillary walls of the caeca, are remarkable for the presence of germ-line vesicles and contain their centrioles near the cell membrane. The spermatocytes and spermatids are flagellated cells arranged in clusters. During spermiogenesis the basal body/flagellum complex migrates to the apical pole of the spermatid. The acrosome-like structure arises from material produced by the Golgi complex. It lacks a surrounding membrane and has a fibrillar content. The nucleus elongates and the condensation of chromatin is caused by an activation of 'initiation centres'. The late spermatid and the spermatozoon appear as two-armed 'V'-shaped cells in which one arm contains the nucleus and posteriorly located mitochondria, and the other one is the axoneme. Spermatogenesis of P. harmeri is an interesting example of gamete differentiation where advanced sperm structure is combined with a plesiomorphic pattern of sperm development characterized as 'flagellate spermatogenesis'. Communicated by H.-D. Franke |
| |
Keywords: | Phoronopsis harmeri Flagellate spermatogenesis Spermatozoon |
本文献已被 SpringerLink 等数据库收录! |
|